"They never told me that they were going to beat them or they were going to put them in a dark room or they were going to fracture him or break his arm," said Veronica Bernal, the mother of one of the children.

"When they didn't do their exercises the way they were supposed to, they were stomped in the back. Their fingers were stepped on," said Araceli Pulido, who had two daughters at the camp.

Of the 37 camp participants, 13 male and female victims, ranging from 12 to 17, claimed they had been assaulted by officers at the camp, sheriff's officials said.

Sheriff's detectives arrested the four officers involved on Tuesday and Wednesday.

The South Gate Police Department issued a statement on its website saying, "We support the San Luis Obispo Sheriff's and the District Attorney's Office regarding the need for transparency in this matter and we will continue to cooperate with them as is necessary and appropriate."

Gomez and Gomez-Marquez were arrested on suspicion of willful cruelty to a child, criminal threats, criminal conspiracy, criminal battery and abuse under color of authority.

Larios was arrested on suspicion of willful cruelty to a child, criminal conspiracy, criminal battery and abuse under color of authority.

Nijland was arrested on suspicion of willful cruelty to a child, criminal battery and abuse under color of authority.